1. Field of the Invention.
The present invention relates to an apparatus and method for transmitting audio and non-audio information, and in particular, to an apparatus and method for transmitting audio and non-audio data with built-in error correction to ensure high quality reception and reproduction of the audio and non-audio information.
2. Description of the Related Art.
Recent developments have enabled users to store a large amount of digitally encoded audio information in a centralized location for easy retrieval and playback. For example, it has become relatively common for a user to “rip” a CD and convert the digital information stored therein to a compressed format, such as MP3, and store the MP3 files onto a hard disk drive of a personal computer. Utilizing such a method, a very large number of audio files can be stored on a single hard disk drive. For example, MP3 encoding at a rate of 128 Kbps corresponds to approximately 1 minute per megabyte of storage, and thus, a 20 GB hard disk can store approximately 20,000 minutes of music. The stored files can then be organized, retrieved, and played back using any one of a plurality of commercially available programs, for example, Musicmatch. The stored files may also be downloaded to a portable player or a portable storage medium, such as a CompactFlash card.
However, there are some limitations to listening to audio files when the files are being processed and played back from a centralized device such as a personal computer. Generally, the user must be in the vicinity of the computer's speakers to listen to the audio files as they are retrieved, processed, and outputted by the computer. Peripheral devices, such as an audio receiver, may be attached to the central device by means of a cable for play back at a remote location, but such a solution may require very long cables, or that the cables be run through walls, and thus, may be impractical. Alternatively, it is known to attach a wireless transmitter to the personal computer, or similar device, to transmit the audio information from the personal computer to a receiver device having speakers attached thereto. However, such transmitters generally utilize traditional analog methods, wherein the personal computer decodes the audio file, processes the decoded file to provide an output audio signal, and the output signal modulates a carrier signal. At the receiver end, the received output audio signal is demodulated to recover the output audio signal, which is used to drive a set of speakers. Such a method is susceptible to the problems associated with analog transmissions, such as interference, and reduced fidelity caused by poor reception.
In that regard, traditional analog methods of transmitting audio information can provide for low cost delivery and reception, but such methods do not offer the fidelity, noise immunity and error correction capability associated with digital transmission and processing methods. Digital modulation/transmission methods, for example, QPSK and FSK, may offer superior performance, but generally requires more expensive components and configurations to implement.
Furthermore, analog methods of transmitting the audio information generally do not easily provide for embedding non-audio information. into the audio information. For example, a compressed audio file, such as an MP3 file, may include non-audio information related to the audio information. The MP3 files include an ID3 tag portion that may include information about the artist, album, etc. It is difficult to transmit this information at the same time with the audio information using analog transmission methods. Additionally, it may be desirable to transmit non-audio information unrelated to the audio information, for example, sports scores, weather information, stock quotes, and the like, along with the audio information.
Therefore, it is desirable to provide a low cost method for transmitting audio information in a manner that provides the benefits of a digital transmission methods. It is further desirable to provide a low cost method for transmitting audio information that includes error detection and/or correction to provide CD-quality reproduction of the audio information.
It is further desirable to provide a low cost method for transmitting audio and non-audio information in a manner that provides the benefits of digital transmission, wherein non-audio information may or may not be related to the transmitted audio information. The non-audio information may be related to the audio information to provide information about, for example, the artist, album, etc. The non-audio information may be unrelated to the audio information to provide general information, for example, sports scores, weather information, stock quotes, or the like.
It is further desirable to provide a method for controlling a decoder associated with a receiving unit for implementing the digital quality transmission in order to prevent an empty or overflow condition in a file buffer associated with the decoder.